In addition to showing that COVID-19 has decreased levels of CD4+ and CD8+ T cells, it has also been shown that the levels of CD4 + T cells expressing CD38− and HLA-DR−, and CD8+ T cells and CD4+PD-1+ T cells, were higher in the proportion of patients with severe COVID-19 compared to healthy people [22,122]. The gene discussed is CD4; the disease is COVID-19.